Corona protection device



BEST AVAILABLE COP.

No'v. 11 1924. 1,515,293

J. B. WHITEHEAD CORONA PROTECTION DEVICE Filed larch 1, 1922 ATTORNEY Y INVENTOR John 5. Wh/Ieheaa Patented Nov. 11, 1924.

BEST AVAlLABLE COP.

- I ED STATES PATIENT; OFFICE.

JOHN B. WHITEHEAD, 0F BALTIMORE, MARYLAND, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMIPANY, A CORPGRATION OF PENNSYLVANI IA.

CORONA rno rnc'rr'on" nnvIcE.

- Application filed March 1, 1922. Serial No, 540,350

' Be it known that I, JOHN B. VVHITEHEA a citizen of the United States, and aresident of Baltimore,.in the Stateof Maryland, have invented a new and useful Improvemerit; in, Corona Protection Devices, of which the follow ingiis a specification.

- This; invention relates to protective devices,v more'particularly tohmea'ns for proy providea device o'f'the abovedesignated character which shall be'simple inl'constructi'onand easy to manufacture; which maybe applied t9 the cable'fito be protected very readily and whichmay beadapted, with tect ing "high-tension alternatingcurrent eablesfrom: abnormal voltages, such as are produced therein by lightning and cloud discharges and sudden changes of loadQ.

A cloud overhead induces charges on apart of the line. I each 'line remains; zero, that is, the alternating current power voltage.alter nately raising and depressing it. When. the

cloud discharges, chargesare left onthe lines immediately ra-isingltheir potential. The charges spread to the ends of theline, tending, to flow to earth in a grounded system or to oscillate back and forth in an ungrounded system to a uniform distribution and gradually leak to ground.

The rise of voltage on discharge of the cloud .may be above. the fla'shover voltage of the insulators and thus discharge at once.

I If not, the wave-front voltage will advance,

with a value and velocity dependent upon the sharpness of the discharge of the cloud, to the end of the line, striking the :reactance ofthe terminal equipment, and thus sufiering reflection. The maximum conditions re-' sult from assuming instantaneous discharge of the cloud, a velocity of propagation equal to that of. light and a doubled value of the' voltage on reflection. v

The absolute rise of voltage above ground is also dependent on the power or dynamic voltage. .The time interval of theelectrostatic disturhances is negligible compared ,with one cycle ofpower voltage. 'Hence,

the electrostatic voltage may occur atany point on -the.alternating-current cycle and so ,be raisedj or lowered thereby. But, since there are 3 three-phase lines, itwould appear that, on one at least,the electrostatic and dynamic voltages would be added together, H v

My invention is adapted to prevent cloud The average potential of except for value 'and rises too slowly.

of this invention to provide. a 'protective device for high-tension lines which Shall cause'eorona to be formed and 'thus' disslpate the'excess' energy and voltage which may be caused in the line by lightning, discharges or' 'cha'nges of'load-f Y It 'isfa further object of my. invention t'o little or no alteration, to lines carrying which are held' s'othat' said members are in contact withthe cable to 'be protected a d proleot radially outward therefrom; "s cificauyT'piride a Series of spring clips adapted to be Held around the cable and I formj'openings' in the ends of said clips.

" The Qs'tud members, which are relatively long and areprovided'fwith heads. are held in the openingsfin'lsaid clips, with the heads of the studs'in contact with the cable.

Such devices, when applied to a high-tension icalile, are capable of causing corona discharge to begun at a small value above the .line voltage. Results of tests with "my new protective device show that there is a critical range of'value of the spacing of the discharge points. Below the range. the coronaformmg voltage 15 raised and above the range, the volume of the discharge is low ered.

I have'iou'nd that the free ends ofthe studs should be rounded, since an ordinary sharp po1n't,'such as is found on barb wire, has been foundunsuitable; The discharge "curve 'of such pointsbegins at too low a Itis desirable that, ahove a'defini-te value of voltage, the volume of discharge from the'studs' should rise sharply' The coronav loss on high-tension lines rises'very sharply, as the square of the excess-voltage above the corona-forming"formation. By a proper design and spacing of the discharge members BEST AVAILABLE C or s uds, it is possible to cause the coronadischarge curve to rise even more sharply than the normal corona-power-loss curve.

Referring to the "accompanying drawing constituting a part hereof and in .'w-hich like reference characters designate like Fig. 1 is a perspective view of a cable equipped with my inventionf Fig. 2 is a plan View ofa spring clip; I

A Fig. 3 is a side view of one of the studs utilized in my invention, and "Fig. A: is 'a'side view of the assembled and completed device ready to be clamped upon acablex I The cable 1- may beof'any suitable type, but is generally made 'of-a number'of strands of metal twisted together. Upon said cable I mount "at suitable intenvals,.-a ,-nun 1ber of spring clips having stud gneinbers thQEQQD iii-such tfliltilflll that thedischarges irom the'stud's do not interfere-with eachg'other. General-1y; therzclips' are 'so studs onalternate clips '81'8"; in -fa aiirection approximately at right angles to the'gadg'acent studs, lbutwthis -speci fic "angular-relation .is notessent ialw I I The spring clip 3 is formedzof sheet steel and has openings 4 providedg-in the ends thereof. eStuds 5; having irou-nded outer ends 4, the gourvature of said ends being shown j-as substan- 7 .cables comprising a projectingf member to 6 are placed in the openings tially equal to the diameters (of the studs but may be of di-fierent -curwature,- if desired. The inner ends oi the studs are provided with heads '7 to engage the inner surface 201 the clip a The ,cltp -3 as bent :on a radius substantially equal to the rad us of 'thecable :upon which it is to be placed, thelength'thereof being such that the heads 7 'shall be more'than 180 apart and the spring action of the clip being such as to press the heads against the .;cable to hold the clip securely in position.

i have placed devices of the above-specified type upon a high-tension cable which 1 was designed to carry power at about 70.000

ivolts. In this case, the studs were one-half inch long and one-eighth inch. in diameter. Two such studs were mounted on each clip and the clips were spaced six inches apart on the cable. This arrangement gavea di charge curve beg-inning at, and rising yery,

sharply above, about 75,000 volts. Normally. on an unprotected line, the voltage necessary to initiate a corona discharge is 'ab0ut200,000' olts. It will, therefore, be seen that'my device is veiy efiective in protecting "a high-voltage line 'in that discharge of abnormal voltage begins when the voltage rises to less than 10% above the normal operating voltage. Furthermore, the volume oi discharge increases very rapidly from the point where. discharge begins I. claimias nventio holding th same man ia wit.

plg dsthat the 1 my invention is-notli'mited to sti ch details. blank .for a.

Obviously tl e design of the clips and studs is determined by the constants of the line ,be protected. I may provide a different arrangement and spacing of the spring clips and difiere-nt dimensions of th e various parts. These andpther changes ,inconstrucbe appanent to those tion of; my device will skilled in the ..a 'nt.

1. A .prp fliie, devi ifi h sl aeeisi cables .comn sms 'afpmjs ing me l a e-eat n d cha e an sa n minated at liii'giieiisipn. same ess a ad ahpmi tin mm- ,bar to vtaoilitate corona; 'd'

area;darts;m r-tea cables leomprisingIa projecting memherghaving itspouter end rounded, the radiusof curvature thereof being substantially :equal to the radius of said member. r

'6. A protective device tor high tension cables comprising a projeeting member and spring .means for holding,the same in contact with said cable. Y

7. A protective device for high-tension cablescomprising a projecting member and a spring clip for holding the same in contact with said cable.

8. A protective device [for hightension cables-comprising a-;plurali ty of projecting members and means for holding the same in contact with said cable V 1 A p w. de i' .for his enls cables comprisin'ga plurality of sets ofvstuds and means for holding the .same.,in, contaet with said cable. i i

10. A protective device for Thigh-tension cables comprising a pluralitvo'f -sets of studs and a plurality of spaced spring clips, said studs being held in contact with'said, cable by means of said clips. Y

11. A protective device for high-tension cables comprising a plurality ofse'ts of studs BEST AVAiLABLE cos,

and a plurality of spaced spring clips hav ing opening in which said studs are located, the heads of said studs being held in contact With said cable by the spring action of said clips.

12. A protective device for high-tension cables comprising a plurality of sets of studs and a plurality of spaced spring clips ha ing openings in the ends thereof in which said studs are located, the heads of said studs being held in contact with said cable by the spring action of said clips.

13. A protective device for high-tension cables comprising a plurality of sets of studs and a plurality of spaced springs clips having openings in the ends thereof in which said studs are located, the heads of said studs being held in contact with said cable by the spring action of said clips, said clips being spaced apart along said cable and being circuinferentially disposed to ensure an angular relation between adjacent sets of studs. I I

14. A protective device for high-tensio cables comprising a plurality of sets of studs and a plurality of spaced spring clips having openings in the ends thereof in Which said studs are located. the heads of said studs being held in contact with said cable by the spring action of said clips, said clips being spaced apart along said cable and being circuinterentially disposed to ensure a staggered relation of said studs longitudinally of said cable.

In testimony whereof, I have hereunto subscribed my name this 9th day of Feby.,

JOHN B. WHITEHEAD. 

